1. Field of Invention
The present invention relates to a method and a circuit for controlling an equalizer, and an equalizing system.
2. Description of Related Art
An equalizer is provided to compensate a signal for high-frequency loss in signal transmission. An equalization gain of the equalizer varies according to a peaking level. However, the signal may be interfered, and thus the signal contains a high-frequency component. After passing through the equalizer, the high-frequency component may be over-compensated. For applications of differential transmission technology, if a large intra-pair skew between a positive signal and a negative signal is present, a significant high-frequency component is generated and added to a transmission signal mixed from the two channels carrying the positive signal and the negative signal respectively. After passing through the equalizer, the high-frequency component of the transmission signal is amplified. Hence, spikes are produced in the equalized transmission signal, which may cause a phase-locked loop (PLL) circuit to lock to a phase and frequency different from that of the original transmission signal.